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  • May 21, 2015

Ravello VM Import Tool - Best Practices and Tips

Ravello’s VM Import Tool

Ravello offers an import tool that enables organizations to easily upload their VMware and KVM VMs to Ravello’s platform in a variety of ways - directly from vCenter or vSphere, as an OVF, or by uploading disk files and images (ISOs, VMDKs, QCOWs).

Factors affecting upload time

As one may expect, the time taken to upload the VM by the import tool depends on -

  1. Size of VM - larger VMs take longer
  2. Bandwidth available - more bandwidth means faster upload
  3. Link characteristics - lossy links take longer

We recently ran some tests using Ravello’s VM import tool to characterize the upload time taken based on the type of link. We emulated the WAN link using the popular tool - WANem - and uploaded a 78 MB ISO file for our tests.

As expected, the upload time was small for links with higher bandwidths (e.g. OC-9, FDDI etc.) and large for links with lower bandwidths (e.g. T-1, ADSL etc.). The following chart should give one a rough estimate of the time it would take to upload a similar sized VM based on the link available (note the logarithmic scale for the bandwidth axis).

Next, we looked into the impact of link characteristics on the upload time. Keeping the bandwidth constant at 10 Mbps (CAT-3), we uploaded the 78 MB ISO file for our tests at different levels of packet loss. As expected, the upload time increases with the increase in packet loss. At greater than 20% packet loss, the upload time increase exponentially - thanks to multiple re-transmissions. It is interesting to note that with packet losses less than 15%, the VM import tool is able to gracefully recover keeping the upload time fairly constant.

Having difficulty uploading?

If you are facing challenges with Ravello Import Tool that cannot be explained by the bandwidth and link characteristics mentioned above, here are some things to look into -

Is system clock of machine running Ravello VM import tool in-sync with NTP?

Amazon’s S3 - home to the VMs in your VM library is sensitive to machine clock timestamps. If the system clock of the machine that is using the upload tool is not set accurately the upload will fail on 1% progress. To get around this issue, sync the system clock to pool.ntp.org

Do you need a proxy to connect to internet?

If your environment requires a proxy to be able to access the internet, you will need configure proxy’s IP in Ravello’s VM Import tool before you can upload. Instructions on how to setup proxy is available in Ravello’s knowledge base.

Are you unable to login to the VM Import tool?

Ungraceful shutdowns, hibernation of the machine running VM Import tool in the middle of an upload has the potential to corrupt the tool database. This can lead to user being unable to login to the tool. To work around this issue, one needs to reset the tool by -

  1. Stopping the Ravello’s VM Import Tool service - On Windows, run services.msc and stop the Ravello VM Import Tool service. On Mac, close the ravello-vm-import-server.
  2. Browse to following folder location and delete all the files with json extension (*.json)
    1. Windows - C:WindowsTemp.ravello
    2. Mac - /Users/<name>/.ravello/
  3. Restart the Ravello’s VM Import Tool service
Is the progress on VM Import Tool stuck at 1%?

The VM Import Tool uploads in chunks. Until the first chunk is fully uploaded the progress bar shows 1%, and as more chunks are uploaded the progress bar gets updated. On slow links, the progress bar show 1% for a long time until the first chunk is uploaded - and then suddenly jump to a higher percentage. If you are concerned that VM Import is not uploading properly, take a peek into the logs to confirm that upload is in progress.

VM Import Tool Logs

Feeling adventurous, and want to explore what is going on behind the scenes? Read on.

1. With your Ravello VM Import Tool running, type in your web-browser

2. Your browser should display the location where the log file for VM Import Tool is being stored

3. On Windows the default location is C:WindowsTemp.ravellostore.log and on Mac OSX the default location is /Users/<name>/.ravello/store.log

4. Open the store.log in Notepad (Windows) or Console (Mac). Following snippet indicates that upload has started

5. Following snippet indicates that upload has completed

If your upload issues persist, please reach out to Ravello Support team with a copy of your store.log, and we will be happy to help.

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